title: Osteocalcin expression by circulating endothelial progenitor cells in patients with coronary atherosclerosis.
abstract: OBJECTIVE
  This study was designed to test whether patients with coronary atherosclerosis have increases in circulating endothelial progenitor cells (EPCs) expressing an osteogenic phenotype.
  
  
  BACKGROUND
  Increasing evidence indicates a link between bone and the vasculature, and bone marrow and circulating osteogenic cells have been identified by staining for the osteoblastic marker, osteocalcin (OCN). Endothelial progenitor cells contribute to vascular repair, but repair of vascular injury may result in calcification. Using cell surface markers (CD34, CD133, kinase insert domain receptor [KDR]) to identify EPCs, we examined whether patients with coronary atherosclerosis had increases in the percentage of EPCs expressing OCN.
  
  
  METHODS
  We studied 72 patients undergoing invasive coronary assessment: control patients (normal coronary arteries and no endothelial dysfunction, n = 21) versus 2 groups with coronary atherosclerosis-early coronary atherosclerosis (normal coronary arteries but with endothelial dysfunction, n = 22) and late coronary atherosclerosis (severe, multivessel coronary artery disease, n = 29). Peripheral blood mononuclear cells were analyzed using flow cytometry.
  
  
  RESULTS
  Compared with control patients, patients with early or late coronary atherosclerosis had significant increases (approximately 2-fold) in the percentage of CD34+/KDR+ and CD34+/CD133+/KDR+ cells costaining for OCN. Even larger increases were noted in the early and late coronary atherosclerosis patients in the percentage of CD34+/CD133-/KDR+ cells costaining for OCN (5- and 2-fold, p < 0.001 and 0.05, respectively).
  
  
  CONCLUSIONS
  A higher percentage of EPCs express OCN in patients with coronary atherosclerosis compared with subjects with normal endothelial function and no structural coronary artery disease. These findings have potential implications for the mechanisms of vascular calcification and for the development of novel markers for coronary atherosclerosis.
authors.affiliation: Division of Cardiology, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Mario
authors.initials: M
authors.lastname: Gössl
authors.forename: Ulrike I
authors.initials: UI
authors.lastname: Mödder
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Atkinson
authors.forename: Amir
authors.initials: A
authors.lastname: Lerman
authors.forename: Sundeep
authors.initials: S
authors.lastname: Khosla
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000235:genetics / Q000378:metabolism*; D016022:Case-Control Studies; D003324:Coronary Artery Disease / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D005819:Genetic Markers; D006801:Humans; D016015:Logistic Models; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D015999:Multivariate Analysis; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis; D012372:ROC Curve; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D018952:Antigens, CD34; D005819:Genetic Markers; D012333:RNA, Messenger; D015675:Osteocalcin